Panic: invalid memory address or nil pointer dereference

[garomonegro]

NodesWithSelectorShouldBe

    runtime error: invalid memory address or nil pointer dereference
runtime.gopanic
	/usr/local/go/src/runtime/panic.go:965
runtime.panicmem
	/usr/local/go/src/runtime/panic.go:212
runtime.sigpanic
	/usr/local/go/src/runtime/signal_unix.go:734
github.com/keikoproj/kubedog/pkg/kubernetes.(*Client).NodesWithSelectorShouldBe
	github.com/keikoproj/kubedog/pkg/kubernetes/kube.go:342

In this case kubernetes.Interface was not set since AKubernetesCluster was not called before calling NodesWithSelectorShouldBe. This should be handle better in this and probably all the other methods.